Recently in MRI apparatuses, the coils referred to as multiple RF coils or phased array coils are heavily used as a reception coil for detecting NMR signals generated from an object to be examined. This type of coil is configured arranging a plurality of high sensitivity small RF receiver coils. Also, an imaging method by thinning out phase encodes through the usage of multiple RF coils is disclosed in Patent Document 1.
This method is referred to as a parallel imaging method, and is for eliminating aliasing generated upon thinning out phase encodes using a character by which sensitivity distribution of the plurality of small RF receiver coils that are forming the multiple RF coil are spatially and mutually different.
Patent Document 1: JP-A-2002-315731
Particularly in Patent Document 1, a method is disclosed for executing unfolding by setting sensitivity of the respective small RF receiver coils in the background region as zero or a fixed number in order to reduce artifacts generated due to noise contained in background of the image.
However, in the parallel imaging method described in Patent Document 1, the image obtained by unfolding process had problems being constrained and having new artifacts generated due to drastic decline of sensitivity information in the boundary between the object region and the background region.